Diamond wear properties in cold plasma jet

• The friction pair performed best friction & wear properties in NPJ.
• NPJ atmosphere can reduce the friction coefficient and tended to be stable.
• Graphitization temperature increased from 885 °C to 1185 °C after treatment with NPJ.

Cold plasma jet is applied to control the contact interface and restrain the diamond wear when cutting ferrous metals. A new generation device was developed to generate stable cold plasma jet under atmospheric pressure. Friction & wear tests and thermal analysis experiments were conducted on a mirror steel NAK80/diamond friction pair in atmospheres of air, nitrogen, and nitrogen cold plasma jet (NPJ), respectively. The friction and diamond graphitization rules were determined through the experiments. Results proved that the friction pair exhibited the best friction and wear properties in NPJ atmosphere. When the rotation speed was ≥ 300 r/min, the nitrogen cold plasma atmosphere was found to reduce the friction coefficient of the friction pair, and the friction coefficient tended to be stable when the load was ≥ 50 N. Moreover, the graphitization temperature of diamond increased from 885 °C to 1185 °C after NPJ treatment.